The James Webb Space Telescope (JWST) has helped provide a snapshot of the formation of a planetary system around a young star for the first time, according to astroboffins.
Along with the Atacama Large Millimeter/submillimeter Array (ALMA), JWST has provided data from HOPS-315, a protostar in the Orion B molecular cloud, which proves a good fit with models of the formation of planets in the early solar system, according to a paper in Nature this week.
In an accompanying paper, Fred Ciesla, professor of planetary science at the University of Chicago, said: “This is the first time that astronomers have been able to see details of the inner structure of such a system. This provides an opportunity to study how planetary systems such as ours were shaped in the first stages of their existence.”
Meteorites – and the stuff trapped in them, called inclusions – have offered scientists a glimpse of the early solar system. Their work has shown calcium–aluminium-rich inclusions (CAIs) were the first solid objects to form in the solar system. Hence, those looking for planets forming outside the solar system are on the hunt for signs of CAIs.
But there are a couple of problems with finding them, Ciesla explained. First, the early stages of star formation can be obscured by dust and gas. The second issue is that CAIs only form very early in the star’s evolution, in the first 100,000 years or so, and finding stars that young is extremely challenging.
Nonetheless, Melissa McClure, Leiden University assistant professor, and colleagues have managed just that because HOPS-315 is oriented such that JWST and ALMA are able to peer through the surrounding envelope of dust and gas. They were also able to find the signatures of crystalline silicates and silicon monoxide (SiO) in the region less than 2.2 astronomical units (the distance between Earth and the Sun) from the protostar.
“This is evidence of the high-temperature conditions required for CAIs to form – models indicate that this occurred in the region that extends out to approximately one AU from the protostar,” the authors wrote.
Ciesla added: “Scientists still don’t know precisely how CAIs form, or how these compounds – which have also been found in comets that formed in the coldest, most distant regions of the solar nebula – were redistributed after they formed in the inner disk.
“Looking further afield, this work raises the question of whether other protoplanetary disks exhibit the same evolutionary pathway as the solar nebula. This will require searches for disks that are similar to HOPS-315, but McClure and her team’s work shows that we have the facilities to do exactly that.” ®